Fig. S1
nrg1bns101/bns101 embryos develop a functional heart and survive to adulthood
(a-b) Cartoon of Talen-induced nrg1 mutation with a 14-base-pair deletion in exon 2 (a); this deletion causes a frame shift leading to a premature stop codon in exon 2 resulting in a predicted truncated protein (b). Notably, the predicted truncated Nrg1 protein in nrg1bns101/bns101 animals lacks the Ig-like, EGF-like and TM domains that have all been reported to be essential for mouse cardiac trabeculation 1, 2, 3. If the first ATG downstream of the 14 bp deletion is used to reinitiate translation, a protein consisting of part of the TM domain and the carboxy terminal domain will be made. However, the type IIIa Nrg1 isoform 4 is not predicted to be affected by the bns101 mutation. (c-d) nrg1bns101/bns101 larvae do not exhibit any gross morphological defects as compared to wild-type; lateral views, anterior to the left; scale bars, 0.5 mm. (e-h) Trabeculation appears unaffected in nrg1bns101 mutants. 120 hpf larvae from Tg(myl7:LIFEACT-GFP); nrg1bns101/+ incrosses imaged by spinning disk confocal microscopy; 2D views (mid-sagittal sections) (e and f), and 3D maximum intensity z-projections (g and h); V: ventricle; arrows point to trabecular cardiomyocytes; scale bars, 50 μm.